US2422310A - Film shoe - Google Patents

Description

June 1.7, 1947.

o. R. YNEMETH FILM SHOE Filed May 22, 1944 jiwenzor Oz'ig fikNenwt/v Patented June 17, 1947 UNI-T ED: STATEPSE ornces:

mesne assignments wto Helene Curtisihulusf tries, Inc a corporation of Illinois- P v Ap 'alication May 22,1944, Seria1Nb;" 536;726 4 Olaims:1- .-(Cl. 271- 2:3)"

Thisinventionnrelates to improvements in: mom" 1 ingupicture apparatus andimoref particularly-hon cerns fa novel film shoe'rfconstructiom :iofmain' tainingsa, film strip in planaupon an associatedi fi1m:sprocket:

An important :o bject of the zpresen't "invention is to providea:new andrimproved fiimrshoeiconum struction of :simple; durable-and. compact'=- con-rr= structi-on anda-which is exceptionally eflicientand convenient ion the intended purpose;

Another object is to provide :a:filmshoe'rwhichw/ in the cpenror non-operating ciondition 'assum'es a position behind the film path: andzafiords max-' imum' working clearance at the iront'of thewfilmiisprocket,---thus: great-1y facilitating threading: of the film. I =Henc'e, the invent-ion sharply; -distin-- l guishes fromconstructions-in which the film shoe is moved onlyradiall-yor tangentiallyaway -from.-=- the film sprocket-a limited distance resultinghin a crowdedconditioneof the-apparatus and olo-- 2o structingefreedom of manipulationcf the :film or e of access to other mechanism in thevicinitzv ofthe film sprocket-w;

Anotherobj ect :resi'des'. in the. iprovision of im-v proved :means. for positively retaining: the film 1525 shoe in operating For nonoperating"position? butv-l enabling quickrand :easy manipulation of the film Y, shoe into either of such positionsms Still another object of the invention is to pro-* vide a filmsshoe which is adjustabler'withrespect to its .operativeappruachto thesfi-lmsprocketi A further object :isto provide an improved film-W shoe=construction.involving at minimumnumben i of simplecomponents which areparticularly sus-M ceptibIeLo-f 10W costqixantityproduction .meth-HBS ods of manufacture Other objects,- features, andadvant'ag'es .oi the invention-.wiIL be apparent fromthe following description anditheiaccompanying' sheet of drawingsiinwhich'z u Figiirelxi a perspective view. of a film shoe' and film sprocket assembly 'embodyin'g'the' fea' turesxof the present invention;

FigTZ is a front elevaticnal vieW' o-f the 'film'l shoe and sprocket assembly.

FigLBis a longitudinal vertical sectional view.

throughthe film shoe and sprocket assembly". 1 taken substantially in the plan'eof line 3-3 of Fig. "2 but showing the "fi1m"shoe in the-"open or non-operating position Fig; 4, is a vhorizontal sectional view taken substantially in theilplane of line 4-4 of FigI -Z.

Having. more particular. reference'to the draw-' ing the :specific I embodimenmof the invention 3 selected for illustration 'is espe-ciallyedapted ion 1a castinig havinean-integral journal bos's m iii-'0 2 L: use 'in therelatively sma ll hom'e' type o'f pm jector such as employslG mm; filnii but obviously theinventi'oncanbe employed w it lm oi any size by "eXerci-s'e of simple mechanical adapta tion According to the' inventioiig a filmshoe' til as 5 cooperatively *associated with a film spro'clre't ll i andboth 'are-operatively mounted to p'roqect out froma mounting plate 12. Th'e 'latter may be jecting to o pesite sides of the' plate 'a nd r iro videdewithi an iaxial bbre rMJI- 'lBearingsret5 may be pressfitt'ed inter-the oppositezends of the-borer MA A shaft l'l rotatablysupported by the-I'b'ear ings "I5 extends beyond the epposite ends of them boss 13 and carries the film sprocket II keyed? onto its front' 'end: while 1 a driving 1 pinion or sprocket gear-r l-fi is keyed to ithe 'opp0site'end w of the shafta FPoWerfor driving thewshaft -vlz'l zand 'thereby the -sprocket H rotatably-is transmittcdthroughathe geer l8 in anysuitable manenemas by means-of achainflnohshownla As best i'seerr in 3, the =portion-of theej'ournal boss |3 extend-ing to the front' of the mounting iplatel2 affords a substantial operating: cleanancabet-ween the adjacent tace-cf the mounting plate and the adjacent end of the fih'flSIlPOC-kfpl t. At:its inner'end' the sprocket ll has a radialfilm :locating' 1 and :retain-irig :fiange'vi 9, forwardly of but adjacenttn 'Whi'Ch iS a series of -radia1-:= sprocket; teeth-2fl edaptefd'to engage -in conven tional marginal sprocket apertures 2 l in a film" strip: 22 threadedover"the sp1o'cl et; In this 'instanceflthe film sprocket! I is designed-to handlesoundtrack film." 5

By preference'the fi'lm shoe 10 is in the form of an elongated"plate adaptewto lie in centeredlongitudinally parall'el relation to the axisef the filmsprocket' H when-in film-holding-relation to I thesprocket. -T0this end,'the film'shoeisformed with: atransversely -concave undercut--23, having'fi a curvature which is complementary l to and con" centric-with the sprocket- 11 in the opera-tingpo':-- sitionof the sh0e.- "The :lengtho-f the under-61117 23 is sligh-t-ly-greaterthan the-length of: thesprecket hold-down H shou1der$ 28 and 29, respectivel'y, "I

3 which project concentrically slightly from the main recessed arcuate surface of the undercut 23 to oppose the extreme margins of the film strip 22 and confine the film 22 to or quite close to the periphery of the film sprocket H. Thus the film 22 is guided for travel substantially centered in the film track.

By reference to Fig. 2 it will be observed that the width of the film shoe IQ, or more properly the arc of the concave undercut 23 is preferably equal to and opposes a section of roughly from one-fourth to one-third of the circumference of the sprocket. This affords quite ample film retaining or confining area in the shoe while at the same time affording ample freedom for substantial range in the preferred tangential angles of approach or recession of the film. Additional tolerance in this respect is contributed by preferably smooth ogee curved contouring to the longitudinal edges of the shoe.

Adjacent to its rear end the film shoe Iilis hingedly mounted upon the mounting plate l2 to enable swinging the shoe into and out of film holding relations to the film sprocket ii. For

this purpose a hinge pin 30 extends transversely through the rear end of the film shoe IE3 and through a pair of spaced hinge lugs or ears 3! formed integral with the mounting plate 12 and appropriately located to project forwardly and receive the film shoe in longitudinally medially centered relation to the film sprocket.

In order to facilitate swinging the film shoe into and out of operative position, an integral forwardly projecting handle or finger hold 32 may be provided at the forward end of the film shoe.

Although the film shoe i0 is freely hinged, its swinging movement is suitably controlled in an improved manner through the medium of a leaf type tension spring 33. Herein the spring 33 is formed with an enlarged mounting head 3 which is appropriately apertured to receive the shank of a securing screw 35 by which the spring is fastened against a mounting pad 37 on the mounting plate I2 in centered relation adjacent to'the rear end of the film shoe 1 0. Extending at a preferably outwardly slanting angle from the mounting head 34 of the spring is an integral tension leg 38 which projects into a spring clearance recess or cut out 39 bifurcating the rear end portion of the film shoe l0. Traversing this bifurcation 39 forwardly of the hinge pin 38 but relatively close to the latter is abutment means such as a pin d0 against which the free end portion of the spring tension leg 38 bears with constant resilient pressure. The location of the abutment pin 48 relative to the spring tension leg 38, and the approach of the spring tension leg to the abutment pin are such that in the closed or operative film-retaining position of the film shoe ID, as seen in Figs. 1, 3 (broken line position) and 4, the spring pressure against the pin i!) is translated into an over-center force tending to urge the film shoe about its hinge pivot firmly toward the film sprocket II. This positively, though resiliently, maintains the film shoe in the operative position.

When the film shoe If! is swung away from the film sprocket H for film threading purposes or the like, the abutment pin 45] also swings on a short are about the axis of the hinge pin 30, and after the film shoe has been opened to the. extent that the pin 40 passes beyond the center of resilient force as indicated by the line C in Fig. 3,'the spring 33 holds the film shoe open. The

film shoe Iii will then be retained in the open position until pushed back to the operating overcenter side of the line C whereupon the spring tension acts to snap the film shoe closed. 7

Although the primary function of the film shoe H1 is to hold the film strip 22 in close engagement with the film sprocket l l the shoe-sprocket inter-relationship must be free from drag, such as would be imposed by the relatively stationary film shoe were it to press against the film upon the sprocket under the influence of the spring 33. Accordingly, stop means is provided for maintaining the film shoe is operatively spaced from the periphery of the film sprocket to afford clearance for the film to move freely between the film shoe and the sprocket while nevertheless confining the film close to the sprocket. Herein such means comprises a stop element 4| in the form of an' adjustment s c r e w threaded perpendicularly through the film shoe l0 intermediate the flange groove 25 and the spring clearance 39 and adapt ed to abut against a bearing pad 42 on the adjacent surface of the journal boss l3. Through the medium of the adjustment stop screw 4!, an optimum film clearance spacing can be attained between the film sprocket I I and the film- opposing shoulders 28 and 29 of the film shoe. Such spacing should, of course, be conditioned to accommodate a film splice. Any adjusted condition of the stop screw H can be maintained by' means of a lock nut d3.

By preference, the adjustment stop screw 4| serves also to stop or delimit the fully open position of the film shoe l B. For this the head of the screw 4! is preferably so disposed relative to the tension spring 33 that when the film shoe I0 is swung far enough open the head of the screw may engage the adjacent face of the spring and resist further opening of the shoe.

While I have illustrated and described a certain preferred embodiment of my invention, it

is to be understood that I do not thereby intend to limit my invention to the specific form disclosed, but contemplate that various modifications, substitutions, and alternative constructions may be effected without departing from the spirit and scope of the invention as defined in the appended claims:

I claim:

1. In combination in a film shoe construction, a film shoe body including means for cooperation with a film sprocket to hold a film strip in place upon the sprocket, means for hingedly mounting 1 the shoe for swinging. into and out of operative positions relative to the film sprocket, an opening in said body adjacent to said hinge means, an elongated leaf spring adapted to be mounted adjacent to the hinge mounting of the shoe and having a tension leg adapted to extend into said opening, and means in said opening providing a bearing for said tension leg to receive resilient thrust therefrom operative to hold the shoe in open or closed position when the shoe is selectively moved into either of said positions.v

2. A film shoe construction as defined in claim 1 in which the shoe body is of elongated form and bifurcated to provide said opening and the bearing means comprises a pin extending across the bifurcation.

3. In combination in a film guiding construction of the character described, a film sprocket, a film shoe cooperative with the sprocket to confine a film strip closely to the sprocket in running thereover, a hinged mounting for said shoe enabling swinging thereof into and out of operative positions relative to the sprocket, means on said shoe limiting movement of the shoe into 0D- erative position, and an elongated leaf spring cooperative with the film shoe to maintain it resiliently in either the operative or inoperative positions, and mounted in angular relation to the shoe opposing the body of the latter when in said inoperative position, said means coacting with the spring to restrain the shoe to a predetermined extent of movement into said inoperative position.

4. In combination in a film shoe construction adapted to be associated with a film sprocket, means for hingedly mounting the film shoe at one end to enable opening and closing movement of the shoe relative to the associated film sprocket, an elongated leaf spring mounted adjacent to the hinge mounting of the shoe, said film shoe having an opening therein affording clearance for receiving said spring, and means on said shoe inwardly from the hinge mounting thereof and bridging said opening engaged by said spring, the inter-engagement of the spring and said means being such that the force of the spring against said means exerted on one side of a given plane through the hinge axis causes the shoe to be urged toward the film sprocket, and force exerted by the spring against said means on the opposite side of said plane retains the shoe in an open position.

OTTO R. NEMETI-I.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS

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